The present invention relates generally to measurement systems, and, more specifically, to a system for measuring concentration in a fluid stream.
A fluid contained in a vessel may have time varying concentrations of specific components therein. One conventional method of measuring the concentrations therein utilizes a relatively expensive and complex laser system which requires optical access to the fluid for determining the concentrations therein. Operators of the equipment must be specifically trained in its use for obtaining accurate results.
It is desirable to measure time-resolved fuel concentration in a fuel and air mixture in a gas turbine combustor, but a typical laser system is not considered to be practical for this application. For example, low Nox premixed combustors often have limited operability and limited life due to the presence of time-resolved fluid dynamics therein which create dynamic pressure fluctuations which may acoustically excite the combustor and effect undesirably large fatigue stresses. It is therefore desirable to provide a measurement system or tool which may be used in the development of low NOx premixed combustors for measuring the time-resolved concentration of fuel in the air as represented by the fuel/air ratio, the reciprocal of which is also conventionally known as the equivalence ratio. In this way, a better understanding of the coupling between the dynamics of the combustor and its fuel system may be evaluated for improving combustor design and performance and reducing undesirable dynamic behavior.
Accordingly, it is desirable to provide a simple and portable system for measuring time-resolved concentration in a fluid stream, such as in the low NOx premixed combustor, at minimal cost and without visual or optical access being required. The system should also be effective for measuring periodic and extremely short duration fluctuations at the excitation frequencies common in the combustor.